Returns the qualified chunk identifier of the current chunk. String chkid# is overwritten with the {qualified chunk identifier} of the current chunk. The qualified chunk identifier of a composite chunk is equal to the extended chunk identifier. The qualified chunk identifier of a regular chunk is composed by concatenating the secondary chunk identifier of the closest #"FORM"# or #"PROP"# composite chunk containing the current chunk, a dot #"."#, and the current chunk identifier, as in #"DJVU.INFO"#. According to the EA IFF 85 identifier scoping rules, the qualified chunk identifier uniquely defines how the chunk data should be interpreted.